Preparing timber backgrounds correctly is essential for a stable and durable tile installation. Timber naturally expands and contracts due to thermal changes, vibration, and differential movement. If the surface is not properly prepared, these movements can cause tiles or grout to crack. Choosing the right covering system allows timber to move without compromising the bond between the surface and the tiles. However, before applying any system, securing the timber background is crucial.
Preparing Timber Backgrounds for Walls
Wooden walls must be fully sealed to prevent moisture absorption. If left unsealed, timber can absorb moisture from adhesives, leading to staining that may bleed through natural stone or glass tiles. Some types of marine plywood contain dyes that can cause reddish or orange stains on the tile surface.
To prevent staining, seal plywood with a two-part primer in dry areas. For intermittently wet areas, apply a waterproof coating before tiling. Always use a flexible adhesive when fixing tiles onto primed timber surfaces, ensuring the bond can withstand minor movement without cracking.
Preparing Timber Backgrounds for Floors
Not all timber surfaces are suitable for tiling. Chipboard and hardboard are not acceptable backgrounds, as they lack the necessary stability. If either material is present, it must be removed or covered with a suitable substrate before tiling begins.
For plywood flooring, ensure it is at least 18mm thick and cross-laid over existing floors. Secure the plywood with screws at a maximum spacing of 300mm to prevent movement. Floorboards must be tightly fixed using twin screw fixings at each joist to minimise flexing.
After securing the timber, prime the floor with a polymer primer before fixing tile backer boards. Lay the boards in a brick pattern, applying a 3-4mm solid bed of pourable flexible adhesive beneath them. Secure the boards with screws at a rate of five fixings per square metre, using washers to prevent screw heads from tearing the board.
In wet areas, cover all screw and washer fixings with waterproof jointing tape to prevent water ingress. Strengthen joints between tile backer boards using scrim jointing tape in dry areas or waterproof jointing tape in wet areas. Apply both tapes in a fine layer of flexible adhesive to create a strong seal.
For areas over 20 square metres, scrim matting should be applied across the entire surface with a fine layer of flexible adhesive. However, if installing mesh-backed underfloor heating, this step is unnecessary.
Using a Detachment Membrane for Timber Backgrounds
A detachment membrane provides an alternative to tile backer boards when preparing timber backgrounds. Thus, eliminating the need for mechanical fixings. Before installing a detachment membrane, secure the timber floor following the same steps used for tile backer boards.
Attach a detachment membrane with the fleece side facing down, using a vinyl floor tile adhesive or manufacturers recommended alternative. Apply the adhesive evenly, ensuring strong adhesion across the entire surface. Seal all joins between rows of matting with a jointing tape fixed with flexible adhesive.
Once the joints have cured and hardened, spread an even layer of adhesive over the detachment membrane to create a smooth tiling surface. Allow the smoothing layer to dry before fixing tiles.
When using a detachment membrane, the tiles must be at least 50x50mm in size. If smaller mosaic tiles are required, the floor must be prepared with tile backer board instead. Additionally, the final adhesive layer over a detachment membrane must not exceed 10mm to maintain stability.
Final Considerations for Timber Backgrounds
Properly preparing timber backgrounds prevents common tiling issues caused by movement, moisture, and instability. Whether using tile backer boards or a detachment membrane, securing the surface ensures a strong foundation for tiles. Following the correct preparation methods will result in a long lasting and professional finish.
For expert advice on preparing timber backgrounds or selecting the best tiling system for your project, get in touch today.
